I know there's not support of ESRI for ArcGIS Desktop, ArcSDE 10 or ArcGIS Server 10 into Windows Server 2012 and SQL Server 2012, but i install this and it Works just fine, installation steps are the same as in Windows Server 2008 R2 and SQL Server 2008.
The only one exception is it mark some kind of error when you try to run web manager for some controls from .NET 3.5, i read that it's due some inhered of main config of the site at IIS Level, anyway y skip this by deleting some lines from the file config.web and the web manager functions with some errors for services, Works well for managing sites. So i avoid this errors for services managing them thought ArcCatalog Directly.
Anything else Works just fine (y), hope that info provide help for you.